It is known that certain histamine H.sub.2 -receptor antagonists are routinely administered orally to patients suffering from certain gastrointestinal conditions such as ulcers, dyspepsia, various reflux indications, and the like. Examples of commonly used histamine H.sub.2 -receptor antagonist include cimetidine, ranitidine and famotidine. These compounds are usually administered orally in the form of tablets or capsules which are intended to be swallowed. Thus, for a substantial portion of patients being treated with a histamine H.sub.2 -receptor antagonist, the taste of the histamine H.sub.2 -receptor antagonist is unimportant. However, there are many segments of the patient population which have difficulty swallowing tablets, and would prefer a more easily ingested dosage form, such as a chewable tablet. Unfortunately, the histamine H.sub.2 -receptor antagonists are known to have an unpalatably bitter taste which must be effectively masked to ensure good patient compliance with chewable tablets.
Attempts to produce palatably acceptable chewable pharmaceutical compositions comprising a histamine H.sub.2 -receptor antagonist include efforts to mask the bitter taste of the histamine H.sub.2 -receptor antagonist with a drug adsorbate, such as a synthetic cationic resin or a silicate taste-masking agent. Other attempts involve the use of an intense sweetener such as aspartame, or the like. Still other attempts have involved the use of a polymeric coating. For example, U.S. Pat. No. 5,260,072 to Roche et al. proposes a chewable tablet of a histamine H.sub.2 -receptor antagonist comprising granules which are formed by rotogranulation of the medicament with a binder and a fine particulate carrier material, and are coated with a polymer blend of cellulose acetate, cellulose acetate butyrate or a combination of both along with polyvinylpyrrolidone.
These attempts at providing a palatably acceptable chewable pharmaceutical composition have not been entirely successful. Accordingly, there remains a need for effective methods of taste-masking histamine H.sub.2 -receptor antagonists for the preparation of palatably acceptable chewable tablets.